TABLE 3: RUNOFF COEFFICIENTS C BY LAND USE AND TYPICAL INLET TIMES *

Land Use	Runoff Coefficients			Inlet Times (minutes)
	Flat1	Rolling2	Steep3
Commercial (CBD)	0.75	0.83	0.91	5
Commercial (Neighborhood)	0.54	0.60	0.66
Industrial	0.63	0.70	0.77	5-10
Garden apartments	0.54	0.60	0.66
Churches	0.54	0.60	0.66
Schools	0.31	0.35	0.39	10-15
Semi-detached residential	0.45	0.50	0.55
Detached residential	0.40	0.45	0.50
Quarter-acre lots	0.36	0.40	0.44
Half-acre lots	0.31	0.35	0.39
Parkland	0.18	0.20	0.22	To Be Computed
NOTES: 1 Flat terrain: 0-2% slopes. 2 Rolling terrain: 2-7% slopes. 3 Steep terrain: greater than 7% slopes.

 

   Interpolation, extrapolation and adjustment for local conditions shall be based on engineering experience and judgment.

   The coefficients of this tabulation are applicable to storms of 5- to 10-year frequencies. Coefficients for less frequent, higher-intensity storms shall be modified as follows:

 

Return Period	Multiply C by:
25	1.1
50	1.2
100	1.25

 

(Ord. 1995-10 Tab. 2, passed 10-13-1995)

* From Ordinance 81-16, Tippecanoe County, Indiana, A General Ordinance Establishing Storm Drainage and Sediment Control, November 1981.